TABLE OF CONTENTS The Agilent model [15, 16] has similar roots as the UCSD model, as it is based on L. Camnitz' model [1]. It was developed at Agilent Technologies in order to overcome the shortcomings in the implementation of the UCSD model. Hence, it follows the same principles, but is formulated consistently. Mainly with respect to the DC model, the Agilent model was formulated in a way to maintain backward compatibility with the UCSD model, if possible. The forward transit time and the bias dependence of the base-collector capacitance are realized by a unified charge function. All formulas are continuously differentiable. The diffusion charge model, therefore, differs from the UCSD model; it was first presented in [16], and implemented in a slightly modified form. Another difference to the UCSD model is the definition of the thermal model. For example, all temperature dependencies are defined with respect to the dynamic junction temperature. The predefined expected temperature parameter of the UCSD model is not used.
The Agilent HBT model characteristics are:
Base currents defined independently without a fixed current gain parameter as in VBIC;
Early and Webster effects;
Empirical model for soft-knee effect;
Excess storage of charges at heterojunction;
Continuously differentiable depletion capacitance model accounting for reach-through (taken from HICUM);
Transit time and collector capacitance variation due to velocity modulation formulated in a consistent way;
Excess transit time due to base pushout;
Partition of the base-emitter junction into intrinsic and extrinsic parts;
Partition of the base-collector capacitance into...
